This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. A. Specific Aims The Specific Aims in the application have not changed and experiments have been conducted in accordance with these aims. We have progressed in our abilities to perform optical recordings of intracellular pH (pHi) from neurons in the spontaneously rhythmic in vitro tadpole brainstem preparation.